1. Field of the Invention
This invention relates to imaging planar antennas. Particularly, this invention relates to dielectric covered planar antennas for terahertz imaging applications.
2. Description of the Related Art
Large focal planes employing thousands of detectors are expected to be required in future astrophysics missions. However, in order to meet the power and mass requirements for such missions, new technology is needed. One applicable novel technology being developed involves the integration of a stack of semiconductor wafers to form a tunable terahertz receiver front end. In addition, terahertz imaging for security applications may also benefit from large heterodyne arrays. Furthermore, multimode corrugated feed horns have also shown very good pattern characteristics, although fabrication becomes difficult using such designs for very large focal planes at high frequencies.
One desirable solution applicable to these systems employs fabrication a monolithic array of antennas on a planar substrate. However, most planar antenna designs produce broad beam patterns, and therefore require additional elements for efficient coupling to the telescope optics, such as substrate lenses or micro-machined horns. See e.g. Rutledge et al., “Integrated-circuit antennas” Infrared and Millimeter-Waves. vol. 10, pp. 1-90, 1983 and Rebeiz, “Millimeter-Wave and Terahertz Integrated Circuit Antennas,” IEEE Proceedings. vol. 80, No. 11, 1992, which are incorporated by reference herein. Although this does not necessarily preclude their use in large arrays, and indeed large arrays using substrate lenses are being investigated; the key issues for such development include resolving the manufacture and assembly of a large “fly's eye” array of lenses. See e.g., Buttgenbach, “An Improved Solution for Integrated Array Optics in Quasi-Optical mm and Submm Receivers: the Hybrid Antenna” IEEE MTT. vol 41, October 1993, which is incorporated by reference herein. While it is also possible to place an array of antennas behind a single lens, optical aberrations tend to limit the size of such an array design.
In view of the foregoing, there is a need in the art for apparatuses and methods for high frequency antenna designs. There is also a need for such apparatuses and methods to utilize cost-effective manufacturing such as with photolithographic techniques, e.g. a monolithic array produced on a planar substrate. There is particularly a need for such apparatuses and methods in imaging applications at terahertz frequencies. These and other needs are met by the present invention as detailed hereafter.